6.(a)Explain how does the exchange of gases occur in plants across the surface of stems, roots and leaves.(5)
(b) How are water and minerals transported in plants?
Answers
Question
Explain how does the exchange of gases occur in plants across the surface of stem, roots and leaves.
ANSWER
In all the three plant parts the exchange of gases takes place through diffusion.
However the surface of a young stem will have stomata, while that of an older stem will have lenticels. The stomatal apparatus consists of a pore called the stoma, a pair of guard cells and subsidiary cells surrounding them. The exchange of gases through the stomatal pore is dependent upon the turgidity of the guard cells. Stomata are mainly present on the surface of the leaves apart from the epidermal surface of young stem. Lenticels are open pores. In roots stomatal pores as well as lenticels are absent, exchange of gases occurs through root hairs.
Question
How Are Water And Minerals Transported In Plants?
Answer
The water from the soil reaches the leaves by the tissue called Xylem. The root hairs on the root absorb water from the soil and through osmosis the water is transported to leaves through the tissue xylem.Xylem- Fundamental tissue for transportation of water . In plants, minerals and water are transported through the xylem cells from soil to the leaves. The xylem cells of the stem, roots, and leaves are interconnected forming a conducting channel reaching all plant parts. The root cells obtain ions from the soil which creates a difference in the concentration of ions between the roots and soil. Thus, there is a continuous water movement into the xylem.
Explanation:
plants ther are tiny pores called stomata on leaves and lenticels in stc
which
given
which
out
facilitate
(during
the exchange of gases. Carbon dioxide is taken in and oxygen
on leaves and lenticels in stem
out (during photosynthesis) and vice
Carbon dioxide is taken in and oxygen SIS) and vice versa during 134 respiration.
(b)Water and minerals are transported within the plant by the Xylem vessels (mainly
in an upward direction); these are part of the vascular system which also includes
Phloem vessels.
Phloem transports the products of photosynthesis within the plant , to all parts
like the stem, roots, fruits etc. in all directions.